The rise of Justin Bieber was such a blinding explosion of hair and smiles and YouTube cuteness that it was easy to miss his music's ironic achievement: its light touch. His first two releases – the 2009 EP My World and 2010's full-length My World 2.0 – were snuggle-fresh and butterfly-light, luxuriating in R&B bubblegum and first-blush puppy lust. At a time when 12-year-olds can get porn on their iPod Touches, the Biebs made flirty innocence thrive.

But Justin's 18 now, legal and, according to Believe, fully lethal. "Swag, swag, swag on you/Chillin' by the fire while we're eating fondue," he sings on the sinewy electro-pop single "Boyfriend," easing the transition from pup to playa in one of the year's more awesome lyrics. On Believe, Biebs' voice has deepened (physically and digitally), the beats are more driving and libidinous, the sonic settings more intense and wide-ranging. Bieber aspires to the tight versatility of his benefactor Usher, who is one of the album's executive producers.

Bieber's revamped sound makes room for universalist Euro-house ("All Around the World") and high-drama hip-hop boom ("As Long as You Love Me"), and on "Right Here," Drake and Bieber go low-talking Lothario to low-talking Lothario. It's cosmopolitan pop sophistication, designed to make this the Bieber album 18-and-over folks can like without feeling like they're joining NAMBLA.

Believe's recently legal euphemisms aren't always smooth. On "Fall," he croons, somewhat ickily, "If you spread your wings, you can fly away with me." Sometimes he barrels through euphemism entirely. The bonus track, "Maria," about a real-life fan's phony paternity suit, is "Billie Jean" by way of Matt Lauer Reports – "She's crazy/Crazy in love!" Bieber sings, sowing his celebrity-victimhood oats. Sometimes, however, the results are excellent and hilarious. On the Max Martin-produced disco-inferno "Beauty and the Beat," Nicki Minaj swoops down like a horny hawk: "Justin Bieber/ You know I'm gonna hit 'em with the ether/Buns out, wiener/But I gotta keep an eye out for Selena."

Bieber doesn't have the soulful vocal snaps of a Justin Timberlake or the shock-and-awe charisma of a Britney Spears. His gently sparkling persona can get overwhelmed by all the sonic gear-switching, technological tomfoolery and sweaty come-ons; it can all feel a bit rushed. The best song on Believe, "Thought of You," has it both ways, combining the impulse to wait with the impulse to get down into a pure-pop fever dream. Over producer Diplo's superhero piano stabs, double-time hand claps and a whoosh-trance build that leads to a chorus Lady Gaga would give her favorite wig for, Bieber goes into spirals of falsetto rapture as a cyclone of contradictory emotion: "I'm in love with the thought of you/Not the things you do," he admits. It's the moment where Justin lives most honestly in the swag-and fondue-deprived world of his fans – crushed out to the point of asphyxiation, pulled in a million directions, chasing feelings he can't understand to consequences he'll probably regret. It's where he's a kid again.